In many popular mobile terminals of today, the keypad can be locked when the phone is not used. There are many ways to implement the keypad lock feature, the most popular terminals using a sequence of two different key-presses to lock the keypad, and some other terminals having features like timer lock or keypad lock selection from the menu. Also, the possibly existing cover of the keypad can be used for locking, or the keypad can be locked when other input options of the electronic device are used.
It is known that the keypad of a mobile phone (or similar device) can be locked e.g. by selecting such an option from a menu or by pressing a certain key combination. The key-locks are used to prevent accidental key-presses, for example if the device is in a pocket or in a purse. However, sometimes the user would like to use the device only for one quick operation, e.g. to read a received SMS (Short Message) or to change the user profile. If the keypad is locked, in ordinary mobile terminals, the user has to unlock the keypad first, then perform the operation and in the end remember to lock the keypad again.
Prior art U.S. Pat. No. 4,845,772 (Motorola) discloses a mobile phone where the keypad is automatically locked following an operation performed by the user (closing a flip element). However, this manner of operation is tied closely to a phone containing a flip element.
Nokia patent application EP 0 939 533 discloses a semi-automatic key-lock where upon closing a sliding cover a softkey for locking the keypad appears on the screen.
Both approaches for key-locks described above have in common that they are not suitable for the use with mobile terminal devices or handheld computers that do not have slideable or flippable covers. Therefore, the above mentioned electronic communication devices fail to overcome the problems related with cover-less mobile electronic devices.
The current solutions, although providing a secure locking mechanism, hamper the use of the terminal for quick operations, while they provide the necessary key-lock function. For example, when the user wants to use the terminal for a single phone call, or if he wants to change the profile of the terminal or to read a received SMS, it is first necessary to unlock the keypad (e.g., two key-presses and a short waiting time), then maybe press a single key to perform the function (dial shortcut, select profile, show message) and after the operation, press two keys to lock the keypad or wait for the lock timeout. This cumbersome operation often leads to user's negligence that the keypad is left unlocked, this in turn perhaps leading to accidental phone calls. While the timer lock solves this problem partly, there is still the timeout period when random key-presses can initiate calls or interfere with the operation of the terminal otherwise, e.g. by terminating a call in progress or entering names into the phonebook.